An improved high-performance logic gate using series diode and resistor loads for ECL/CML applications

An improved high-performance logic gate comprised of a series collector-base shorted n-p-n transistor diode and resistor as the load element for emitter-coupled logic/current-mode logic (ECL/CML) applications is presented. This load element has been shown to provide up to a 50% performance improvement in ring-oscillator gate delay. A comparison between typical load elements was conducted to demonstrate the effect of the active load. The physical mechanism that accounts for the performance improvement is identified as the inductivelike impedance characteristic of the active load. Analytical results and computer simulation are given to support the mode. Measured data are in excellent agreement with the computer simulation. In addition, this load element is found to be comparable with typical ECL/CML applications.<
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